Extended map display shader mechanism.

- Inverted shader call logic
	- Instead of mapDisplay calling shader() on itself, the mapDisplay is
passed to the Shader
	- Allows more complex shading behaviour, e.g. a two-pass Gaussian Blur.

- Created super class MapDisplayShader

- Two shade() methods can be implemented, shadeWithMarker and
shadeWithoutMarker
	- Which are called at different positions in postDraw() from
mapDisplay.

- Enhanced MaskedMapDisplayShader, now has two options:
	a) use dynamic mask canvas
	b) use mask image

- Added Blur and Deform shader

- Added shading examples
Updated more examples and tests to Processing2.
Fixed MapDisplayFactory to create mapDisplays for P2D renderer (but does not work fully)